1. Field of the Invention
The present invention is directed to a flexible polyurethane foam which does not drip while burning. More particularly, the drip-free flexible polyurethane foam of the invention contains a polyamine functional silicone polymer or an active polyhydroxyl functional silicone copolymer in exceptionally small amounts to effectively prevent the flexible foam from dripping while burning.
2. Description of the Related Art
Flexible polyurethane foams have a wide variety of applications, from seat cushions in aircraft, automobiles, and furniture to carpet underlay, dashboards, headrests, and packaging materials. However, polyurethane flexible foams are plagued with flammability problems, leading to the melting and spreading of burning foam through molten or flaming droplets. The molten or flaming foam dripping from the original mass not only can cause the remaining unburnt foam to smolder, but also presents a risk of smoldering or igniting encasements or objects in the nearby vicinity.
Flame retardants do not solve, and often exacerbate, the problem of smoldering and dripping. Some flame retardants encourage the formation of drip to quickly remove the burning mass from the unburnt mass, thereby quickly extinguishing the flame. For many applications, however, there exists a need to contain and localize the burning mass rather than allow flaming or molten drippings to spread and thereby risk smoldering and igniting other nearby flammable objects.